Pain - MUST University PDF

Dr. Mona Elsheikh Lecturer at department of Physical Therapy for Neurological Disorders and its Surgery Faculty of Physical Therapy, MUST univ. Mission and Vision of the College of Physical Therapy – Misr University for Science and...

Dr. Mona Elsheikh Lecturer at department of Physical Therapy for Neurological Disorders and its Surgery Faculty of Physical Therapy, MUST univ. Mission and Vision of the College of Physical Therapy – Misr University for Science and Technology (MUST)  Pain is an unpleasant sensation, a feeling of discomfort resulting from stimulation of pain receptors in the body when tissue damage occurs or is about to occur.  Pain is a body defense mechanism and is a warning of a problem, particularly when it is acute.  It is difficult to define because it can have many variable characteristics, and it is a subjective feeling, impossible to accurately measure.  However, subjective scales have been developed to compare pain levels over time.  Etiology and Sources of Pain Organs Skeletal muscle & Stomach and General (such as the liver, joints intestines kidney, or brain)  Infection,  Ischemia or hemorrhage  Pain receptors in pain may result from  Ischemia  Stretching of tendons, the covering inflammation of the  Tissue necrosis, ligaments, and joint capsule, and pain is mucosa, ischemia,  Stretching of tissue, capsules also elicits pain; felt when the distention, or muscle Chemicals, or burns. these effects may occur capsule is stretched spasm. secondary to by inflammation. inflammation or muscle spasm to guard a joint or painful body part.  Etiology and Sources of Pain Somatic pain Visceral pain Arise from the skin (cutaneous) or from pain originates in the deeper structures such as organs and bone or muscle travels by sympathetic Conducted by sensory fibers nerves.  Depending on the cause, pain may be: Sudden Relatively continuous Short term Long term Marked primarily by infection or a reflex withdrawal. swelling For example, if one touches a hot object, the hand is involuntarily jerked away from the source of injury. Structures and Pain Pathways  Pain receptors or nociceptors: are free sensory nerve endings that are present in most tissues of the body  Lateral Spinothalamic Tract  Medulla (Reticular Formation)  Thalamus (sensory relay center) Hypothalamus (stress response) Limbic system (emotional response)  Somatosensory cortex parietal lobe locate pain The pain threshold refers to the level of stimulation required to activate the nerve ending sufficiently for the individual to perceive pain. The pain threshold is relatively constant over time and among individuals. Pain tolerance is the ability to withstand pain or the perception of its intensity; this varies considerably with past pain experience and overall state of health.  Types of afferent fibers A Delta Fibers C fibers That transmit impulses rapidly That transmit impulses slowly Acute pain—the sudden, sharp, Chronic pain—often experienced as a localized pain related to diffuse, dull, burning or aching thermal and physical stimuli sensation. primarily from skin and Receive thermal, physical, mucous membranes and chemical stimuli from muscle, Travel in the neospinothalamic tendons, the myocardium, and the tract digestive tract as well as from the skin. Travel in the paleospinothalamic tract.  Each spinal nerve conducts impulses from a specific area of the skin called a dermatome (the areas of the skin innervated by each spinal nerve),  The somatosensory cortex is “mapped” to correspond to areas of the body so that the brain can interpret the source of the pain  The dermatomes can be used to test for areas of sensory loss or pain sensation and thus determine the site of damage after spinal cord injuries.  A reflex response (At the spinal cord synapse) to sudden pain results in a motor, or efferent, impulse back to the muscles that initiates an involuntary muscle contraction to move the body away from the source of pain.  Physiology of Pain and Pain Control The gate-control theory Open According to this theory, control systems, or “gates,” are built into the normal pain pathways in the body that can modify the entry of pain stimuli into the spinal cord and brain. These gates at the nerve synapses in the spinal cord and brain can be open, thus permitting the pain impulses to pass from the peripheral nerves to the spinothalamic tract and ascend to the brain. Or they may be Closed, reducing or modifying the passage of pain impulses. Gate closure can occur in response to other sensory stimuli along competing nerve pathways that may diminish the pain sensations by modulating or inhibiting impulses from higher centers in the brain. Gate open Gate closed  For example, the application of ice to a painful site may reduce pain because one is more aware of the cold than the pain.  Transcutaneous electrical nerve stimulation (TENS) is a therapeutic intervention that increases sensory stimulation at a site, thus blocking pain transmission.  Alternatively, the brain can inhibit or modify incoming pain stimuli by producing efferent or outgoing transmissions through the reticular formation. Many factors can activate this built-in control system, including prior conditioning, the emotional state of the affected person, or distraction by other events.  The key to this analgesia system, or the blocking of pain impulses to the brain, is the release of a number of opiate-like chemicals (opioids) secreted by interneurons within the central nervous system. These substances block the conduction of pain impulses into the central nervous system.  They resemble the drug morphine, which is derived from opium and is used as an analgesic (a pain blocking or relieving medication), and are therefore called endorphins or endogenous morphine.  Serotonin is another chemical released in the spinal cord that acts on other neurons in the spinal cord to increase the release of enkephalins.  Clients with clinical depression often report chronic pain due to a reduction in serotonin levels in the brain.  The body has its own endogenous analgesic or pain control system that explains some of the variables in pain perception and can be used to assist in pain control.